linux/drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c
Nathan Chancellor 96d845a67b drm/fsl-dcu: Fix return type of fsl_dcu_drm_connector_mode_valid()
With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG),
indirect call targets are validated against the expected function
pointer prototype to make sure the call target is valid to help mitigate
ROP attacks. If they are not identical, there is a failure at run time,
which manifests as either a kernel panic or thread getting killed. A
proposed warning in clang aims to catch these at compile time, which
reveals:

  drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c:74:16: error: incompatible function pointer types initializing 'enum drm_mode_status (*)(struct drm_connector *, struct drm_display_mode *)' with an expression of type 'int (struct drm_connector *, struct drm_display_mode *)' [-Werror,-Wincompatible-function-pointer-types-strict]
          .mode_valid = fsl_dcu_drm_connector_mode_valid,
                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  1 error generated.

->mode_valid() in 'struct drm_connector_helper_funcs' expects a return
type of 'enum drm_mode_status', not 'int'. Adjust the return type of
fsl_dcu_drm_connector_mode_valid() to match the prototype's to resolve
the warning and CFI failure.

Link: https://github.com/ClangBuiltLinux/linux/issues/1750
Reported-by: Sami Tolvanen <samitolvanen@google.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221102154215.78059-1-nathan@kernel.org
2022-11-18 09:17:13 -08:00

140 lines
3.5 KiB
C

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright 2015 Freescale Semiconductor, Inc.
*
* Freescale DCU drm device driver
*/
#include <linux/backlight.h>
#include <linux/of_graph.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_bridge.h>
#include <drm/drm_of.h>
#include <drm/drm_panel.h>
#include <drm/drm_probe_helper.h>
#include <drm/drm_simple_kms_helper.h>
#include "fsl_dcu_drm_drv.h"
#include "fsl_tcon.h"
int fsl_dcu_drm_encoder_create(struct fsl_dcu_drm_device *fsl_dev,
struct drm_crtc *crtc)
{
struct drm_encoder *encoder = &fsl_dev->encoder;
int ret;
encoder->possible_crtcs = 1;
/* Use bypass mode for parallel RGB/LVDS encoder */
if (fsl_dev->tcon)
fsl_tcon_bypass_enable(fsl_dev->tcon);
ret = drm_simple_encoder_init(fsl_dev->drm, encoder,
DRM_MODE_ENCODER_LVDS);
if (ret < 0)
return ret;
return 0;
}
static void fsl_dcu_drm_connector_destroy(struct drm_connector *connector)
{
drm_connector_unregister(connector);
drm_connector_cleanup(connector);
}
static const struct drm_connector_funcs fsl_dcu_drm_connector_funcs = {
.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
.destroy = fsl_dcu_drm_connector_destroy,
.fill_modes = drm_helper_probe_single_connector_modes,
.reset = drm_atomic_helper_connector_reset,
};
static int fsl_dcu_drm_connector_get_modes(struct drm_connector *connector)
{
struct fsl_dcu_drm_connector *fsl_connector;
fsl_connector = to_fsl_dcu_connector(connector);
return drm_panel_get_modes(fsl_connector->panel, connector);
}
static enum drm_mode_status
fsl_dcu_drm_connector_mode_valid(struct drm_connector *connector,
struct drm_display_mode *mode)
{
if (mode->hdisplay & 0xf)
return MODE_ERROR;
return MODE_OK;
}
static const struct drm_connector_helper_funcs connector_helper_funcs = {
.get_modes = fsl_dcu_drm_connector_get_modes,
.mode_valid = fsl_dcu_drm_connector_mode_valid,
};
static int fsl_dcu_attach_panel(struct fsl_dcu_drm_device *fsl_dev,
struct drm_panel *panel)
{
struct drm_encoder *encoder = &fsl_dev->encoder;
struct drm_connector *connector = &fsl_dev->connector.base;
int ret;
fsl_dev->connector.encoder = encoder;
ret = drm_connector_init(fsl_dev->drm, connector,
&fsl_dcu_drm_connector_funcs,
DRM_MODE_CONNECTOR_LVDS);
if (ret < 0)
return ret;
drm_connector_helper_add(connector, &connector_helper_funcs);
ret = drm_connector_register(connector);
if (ret < 0)
goto err_cleanup;
ret = drm_connector_attach_encoder(connector, encoder);
if (ret < 0)
goto err_sysfs;
return 0;
err_sysfs:
drm_connector_unregister(connector);
err_cleanup:
drm_connector_cleanup(connector);
return ret;
}
int fsl_dcu_create_outputs(struct fsl_dcu_drm_device *fsl_dev)
{
struct device_node *panel_node;
struct drm_panel *panel;
struct drm_bridge *bridge;
int ret;
/* This is for backward compatibility */
panel_node = of_parse_phandle(fsl_dev->np, "fsl,panel", 0);
if (panel_node) {
fsl_dev->connector.panel = of_drm_find_panel(panel_node);
of_node_put(panel_node);
if (IS_ERR(fsl_dev->connector.panel))
return PTR_ERR(fsl_dev->connector.panel);
return fsl_dcu_attach_panel(fsl_dev, fsl_dev->connector.panel);
}
ret = drm_of_find_panel_or_bridge(fsl_dev->np, 0, 0, &panel, &bridge);
if (ret)
return ret;
if (panel) {
fsl_dev->connector.panel = panel;
return fsl_dcu_attach_panel(fsl_dev, panel);
}
return drm_bridge_attach(&fsl_dev->encoder, bridge, NULL, 0);
}